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CVE-2026-56389 is an OS command injection vulnerability in GNU Bison HTML report generation. When processing a grammar with the HTML-report option, Bison accepts the grammar-defined tool.xsltproc configuration value without restriction. This value overrides the executable used for the XML-to-HTML transformation and is passed directly to execvp(), enabling a malicious grammar to select an arbitrary program for execution. GNU Bison 3.8.2 was confirmed vulnerable; the full affected-version range is not available.
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A vulnerability tracked as CVE-2026-56389 affecting the Bison package on supported Ubuntu Linux releases; the supplied content does not specify the underlying flaw type.
A reported vulnerability affecting GNU Bison software.
An OS command injection vulnerability in GNU Bison's HTML report generation that allows attacker-provided grammar files to trigger arbitrary program execution.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.